1/*
2 * MIPS specific _mcount support
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License.  See the file "COPYING" in the main directory of this archive for
6 * more details.
7 *
8 * Copyright (C) 2009 Lemote Inc. & DSLab, Lanzhou University, China
9 * Copyright (C) 2010 DSLab, Lanzhou University, China
10 * Author: Wu Zhangjin <wuzhangjin@gmail.com>
11 */
12
13#include <linux/export.h>
14#include <asm/regdef.h>
15#include <asm/stackframe.h>
16#include <asm/ftrace.h>
17
18	.text
19	.set noreorder
20	.set noat
21
22	.macro MCOUNT_SAVE_REGS
23	PTR_SUBU	sp, PT_SIZE
24	PTR_S	ra, PT_R31(sp)
25	PTR_S	AT, PT_R1(sp)
26	PTR_S	a0, PT_R4(sp)
27	PTR_S	a1, PT_R5(sp)
28	PTR_S	a2, PT_R6(sp)
29	PTR_S	a3, PT_R7(sp)
30#ifdef CONFIG_64BIT
31	PTR_S	a4, PT_R8(sp)
32	PTR_S	a5, PT_R9(sp)
33	PTR_S	a6, PT_R10(sp)
34	PTR_S	a7, PT_R11(sp)
35#endif
36	.endm
37
38	.macro MCOUNT_RESTORE_REGS
39	PTR_L	ra, PT_R31(sp)
40	PTR_L	AT, PT_R1(sp)
41	PTR_L	a0, PT_R4(sp)
42	PTR_L	a1, PT_R5(sp)
43	PTR_L	a2, PT_R6(sp)
44	PTR_L	a3, PT_R7(sp)
45#ifdef CONFIG_64BIT
46	PTR_L	a4, PT_R8(sp)
47	PTR_L	a5, PT_R9(sp)
48	PTR_L	a6, PT_R10(sp)
49	PTR_L	a7, PT_R11(sp)
50#endif
51	PTR_ADDIU	sp, PT_SIZE
52	.endm
53
54	.macro RETURN_BACK
55	jr ra
56	 move ra, AT
57	.endm
58
59/*
60 * The -mmcount-ra-address option of gcc 4.5 uses register $12 to pass
61 * the location of the parent's return address.
62 */
63#define MCOUNT_RA_ADDRESS_REG	$12
64
65#ifdef CONFIG_DYNAMIC_FTRACE
66
67NESTED(ftrace_caller, PT_SIZE, ra)
68	.globl _mcount
69_mcount:
70EXPORT_SYMBOL(_mcount)
71	b	ftrace_stub
72#ifdef CONFIG_32BIT
73	 addiu sp,sp,8
74#else
75	 nop
76#endif
77
78	/* When tracing is activated, it calls ftrace_caller+8 (aka here) */
79	MCOUNT_SAVE_REGS
80#ifdef KBUILD_MCOUNT_RA_ADDRESS
81	PTR_S	MCOUNT_RA_ADDRESS_REG, PT_R12(sp)
82#endif
83
84	PTR_SUBU a0, ra, 8	/* arg1: self address */
85	PTR_LA   t1, _stext
86	sltu     t2, a0, t1	/* t2 = (a0 < _stext) */
87	PTR_LA   t1, _etext
88	sltu     t3, t1, a0	/* t3 = (a0 > _etext) */
89	or       t1, t2, t3
90	beqz     t1, ftrace_call
91	 nop
92#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
93	PTR_SUBU a0, a0, 16	/* arg1: adjust to module's recorded callsite */
94#else
95	PTR_SUBU a0, a0, 12
96#endif
97
98	.globl ftrace_call
99ftrace_call:
100	nop	/* a placeholder for the call to a real tracing function */
101	 move	a1, AT		/* arg2: parent's return address */
102
103#ifdef CONFIG_FUNCTION_GRAPH_TRACER
104	.globl ftrace_graph_call
105ftrace_graph_call:
106	nop
107	 nop
108#endif
109
110	MCOUNT_RESTORE_REGS
111	.globl ftrace_stub
112ftrace_stub:
113	RETURN_BACK
114	END(ftrace_caller)
115
116#else	/* ! CONFIG_DYNAMIC_FTRACE */
117
118NESTED(_mcount, PT_SIZE, ra)
119EXPORT_SYMBOL(_mcount)
120	PTR_LA	t1, ftrace_stub
121	PTR_L	t2, ftrace_trace_function /* Prepare t2 for (1) */
122	beq	t1, t2, fgraph_trace
123	 nop
124
125	MCOUNT_SAVE_REGS
126
127	move	a0, ra		/* arg1: self return address */
128	jalr	t2		/* (1) call *ftrace_trace_function */
129	 move	a1, AT		/* arg2: parent's return address */
130
131	MCOUNT_RESTORE_REGS
132
133fgraph_trace:
134#ifdef	CONFIG_FUNCTION_GRAPH_TRACER
135	PTR_LA	t1, ftrace_stub
136	PTR_L	t3, ftrace_graph_return
137	bne	t1, t3, ftrace_graph_caller
138	 nop
139	PTR_LA	t1, ftrace_graph_entry_stub
140	PTR_L	t3, ftrace_graph_entry
141	bne	t1, t3, ftrace_graph_caller
142	 nop
143#endif
144
145#ifdef CONFIG_32BIT
146	addiu sp, sp, 8
147#endif
148
149	.globl ftrace_stub
150ftrace_stub:
151	RETURN_BACK
152	END(_mcount)
153
154#endif	/* ! CONFIG_DYNAMIC_FTRACE */
155
156#ifdef CONFIG_FUNCTION_GRAPH_TRACER
157
158NESTED(ftrace_graph_caller, PT_SIZE, ra)
159#ifndef CONFIG_DYNAMIC_FTRACE
160	MCOUNT_SAVE_REGS
161#endif
162
163	/* arg1: Get the location of the parent's return address */
164#ifdef KBUILD_MCOUNT_RA_ADDRESS
165#ifdef CONFIG_DYNAMIC_FTRACE
166	PTR_L	a0, PT_R12(sp)
167#else
168	move	a0, MCOUNT_RA_ADDRESS_REG
169#endif
170	bnez	a0, 1f	/* non-leaf func: stored in MCOUNT_RA_ADDRESS_REG */
171	 nop
172#endif
173	PTR_LA	a0, PT_R1(sp)	/* leaf func: the location in current stack */
1741:
175
176	/* arg2: Get self return address */
177#ifdef CONFIG_DYNAMIC_FTRACE
178	PTR_L	a1, PT_R31(sp)
179#else
180	move	a1, ra
181#endif
182
183	/* arg3: Get frame pointer of current stack */
184#ifdef CONFIG_64BIT
185	PTR_LA	a2, PT_SIZE(sp)
186#else
187	PTR_LA	a2, (PT_SIZE+8)(sp)
188#endif
189
190	jal	prepare_ftrace_return
191	 nop
192	MCOUNT_RESTORE_REGS
193#ifndef CONFIG_DYNAMIC_FTRACE
194#ifdef CONFIG_32BIT
195	addiu sp, sp, 8
196#endif
197#endif
198	RETURN_BACK
199	END(ftrace_graph_caller)
200
201	.align	2
202	.globl	return_to_handler
203return_to_handler:
204	PTR_SUBU	sp, PT_SIZE
205	PTR_S	v0, PT_R2(sp)
206
207	jal	ftrace_return_to_handler
208	 PTR_S	v1, PT_R3(sp)
209
210	/* restore the real parent address: v0 -> ra */
211	move	ra, v0
212
213	PTR_L	v0, PT_R2(sp)
214	PTR_L	v1, PT_R3(sp)
215	jr	ra
216	 PTR_ADDIU	sp, PT_SIZE
217#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
218
219	.set at
220	.set reorder
221